:root {
  /* NIRD Colors */
  --primary: #2563eb; /* Bleu NIRD */
  --secondary: #bf53b8; /* Mauve NIRD */
  --tertiary: #ddb858; /* Orange NIRD */
  --accent: #f49bad; /* Rose NIRD */

  --background: #f8fafc;
  --surface: #ffffff;
  --text: #1e293b;
  --text-light: #64748b;
  --border: #e2e8f0;
  --error: #ef4444;
  --success: #10b981;

  --radius: 12px;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1),
    0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1),
    0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI',
    sans-serif;
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

/* Auth Container */
.auth-container {
  width: 100%;
  max-width: 450px;
}

.auth-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 40px;
}

.auth-header {
  text-align: center;
  margin-bottom: 32px;
}

.logo {
  font-size: 32px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 8px;
}

.tagline {
  color: var(--text-light);
  font-size: 14px;
}

/* Tabs */
.auth-tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 24px;
  border-bottom: 2px solid var(--border);
}

.tab-btn {
  flex: 1;
  padding: 12px 16px;
  background: none;
  border: none;
  color: var(--text-light);
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  position: relative;
  transition: color 0.2s;
}

.tab-btn:hover {
  color: var(--text);
}

.tab-btn.active {
  color: var(--primary);
}

.tab-btn.active::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--primary);
}

/* Forms */
.auth-form {
  display: none;
}

.auth-form.active {
  display: block;
}

.form-group {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 8px;
  font-weight: 600;
  font-size: 14px;
  color: var(--text);
}

input[type='text'],
input[type='password'] {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid var(--border);
  border-radius: 8px;
  font-size: 16px;
  transition: all 0.2s;
  font-family: inherit;
}

input[type='text']:focus,
input[type='password']:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(30, 58, 138, 0.1);
}

input[type='text']:invalid:not(:placeholder-shown),
input[type='password']:invalid:not(:placeholder-shown) {
  border-color: var(--error);
}

.form-hint {
  display: block;
  margin-top: 4px;
  font-size: 12px;
  color: var(--text-light);
}

/* Buttons */
.btn {
  width: 100%;
  padding: 14px 24px;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover {
  background: #1e40af;
  transform: translateY(-1px);
  box-shadow: var(--shadow);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-primary:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* Error Message */
.error-message {
  margin-top: 16px;
  padding: 12px 16px;
  background: #fef2f2;
  border: 1px solid #fecaca;
  border-radius: 8px;
  color: var(--error);
  font-size: 14px;
  display: none;
}

.error-message:not(:empty) {
  display: block;
}

/* Responsive */
@media (max-width: 480px) {
  .auth-card {
    padding: 24px;
  }

  .logo {
    font-size: 28px;
  }
}